1. Field of the Invention
The embodiments of the invention relate to x-ray cassettes and computed radiography plates. Specifically, embodiments of the invention relate to a system for creating images from a plate in a cassette and erasing the plate with improved reusability of the plate.
2. Background
Traditional x-ray film has been used for decades. 28 years ago, a fundamental innovation by Kodak created the first version of a re-usable X-ray plate instead of film. These Computed Radiography (CR) plates store a latent image in a photostimulatable storage phosphor plate. Fuji improved on the Kodak concept and produced the first medical X-ray images using this technique. The CR plate is reflective and erasable allowing repeated exposures, the number of possible exposures is greater than 150,000 if there are no mechanical stresses on the material. An x-ray impregnates the plate with energy which, when subsequently exposed to a particular excitation, is released, recreating the image. Scanners or CR readers of these plates typically include a flying spot laser and photomultiplier tube sensor. The photo multiplier tube captures the image corresponding to the energy being released by excitation of the flying spot laser. The plate is traditionally removed from a cassette and transported by a drive mechanism, typically a set of rollers. This roller type reading process necessitates that the phosphorescent plate be flexible. The feed mechanism used for scanning the plates is typically a set of pinch rollers. Over time the flexing and contact with the rollers causes a deleterious effect on the plate resulting in limited reusability. The phosphor materials in the plates do not degrade due to read/write cycles if mechanical and physical stresses do not act on the plate. Additional wear and tear on the plate is caused by the removal and replacement of the plate in a cassette that protects the plate from ambient energy (light) sources during transportation. In addition to causing degradation of the quality of the plate the pinch rollers can slip causing line artifacts and blurring of the image being generated.